26 - Viral Infections of the Respiratory Tract I Flashcards
1
Q
How many particles are released with each sneeze?
A
20,000
2
Q
What percent of acute illnesses of the upper respiratory tract are caused by viruses?
A
80%
3
Q
Do respiratory viruses tend to maintain consistency or demonstrate seasonal variation?
A
Seasonal variation
4
Q
Upper respiratory pathogens often replication better at what temperature?
A
33-35 degrees celcius, which is a little cooler than 37 degrees, body temperature
5
Q
What do viruses cause?
A
The viruses can cause disease on their own, but that can also predispose the patients to bacterial super-infections
6
Q
What are two of the ways in which viruses predispose to bacterial super-infections?
A
1 - Interruption of mucociliary escalator
2 - Weaken immune system
7
Q
What is the most common upper respiratory illness?
A
The common cold
8
Q
What are the symptoms of the common cold?
A
- Rhinitis
- Pharyngitis
- No high fever
- No lower respiratory tract involvement
- No respiratory distress
9
Q
What is rhinitis?
A
Inflammation of the nasal mucosa (gives you runny nose, stuffy nose)
10
Q
What is pharyngitis?
A
Sore throat (sometimes a mild cough as well)
11
Q
Is the common cold considered a severe infection?
A
No, not severe
12
Q
How frequently do patients typically contract the common cold?
A
Adults
- 2-3 times per year
Children
- 6-8 times per year
13
Q
When does the common cold tend to peak?
A
Fall and spring
14
Q
What are some possible complications you can see with the common cold?
A
- Otitis media
- Sinus infections
15
Q
What is the main causative agent of the common cold?
A
Rhinovirus
16
Q
What are the four possible causative agents of the common cold?
A
1 – Rhinovirus
2 – Unidentified
3 – Other known viruses
4 – Coronavirus
17
Q
In general, all colds are through to be caused by _________
A
Viruses
18
Q
What family of viruses is the rhinovirus from?
A
The picornavirus family
(the name tells you what it is - “pico” = small, “rna” = RNA
It is a small RNA virus
19
Q
Is the rhinovirus stable in the environment?
A
Yes
20
Q
Is the rhinovirus enveloped?
A
No, no envelope is found surrounding the rhinovirus
21
Q
What type of genome do you see in the rhinovirus?
A
+ ssRNA genome
22
Q
There are three viral species of the rhinovirus. What are they?
A
1 - Human Rhinovirus A
2 - Human Rhinovirus B
3 - Human Rhinovirus C
23
Q
How many different serotypes of the rhinovirus circulate in the human population?
A
Over 100
24
Q
Why is this problematic?
A
It poses a problem for trying to “pin it down”
25
How is the rhinovirus spread?
It is shed in respiratory secretions
26
What are the three ways you can transmit rhinovirus?
1 - Direct contact with nasal secretions
2 - Large droplets
3 - Contaminated formities
(Formities: any object or substance capable of carrying infectious organisms, such as germs or parasites, and hence transferring them from one individual to another)
27
How much inoculum is needed for the virus to spread?
Very little virus is needed to cause an infection
The level that was transmitted and caused an infection was too low to be detectable by the laboratory
28
What does the rhinovirus exacerbate in school-age children?
Asthma
29
What does the rhinovirus exacerbate in adults?
COPD
30
What is the pathologic mechanism of the rhinovirus?
1 - Virus attaches to cilia in nasal canal
2 - Enters cell
3 - Disruption of cilia layer
4 - Outpouring of clear fluid from these cells
5 - Cell damage of cells as virus spreads
6 - Host generates antibodies to the virus
7 - Epithelium will regenerate
8 - No further signs of the virus
31
What is the treatment for a rhinovirus infection?
Aimed to alleviate symptoms
- Antihistamines
- Decongestants
32
When would antibiotics be used?
Antibiotics only given in the case of bacterial superinfections because antibiotics will not do anything to the virus itself
33
Will you get long lasting immunity to the rhinovirus after you get it and recover?
Yes, but only to the serotype you contracted... There are 100+ serotypes of the rhinovirus, so this will not prevent further illness
34
Is there a vaccine available for the rhinovirus?
No, you would need many serotypes in the virus, so it doesn't make sense
35
What is the non-SARS coronavirus?
Another virus that can cause the common cold
36
Why are they named "corona" viruses?
Named based on the way they look under the microscope
Glycoprotein ring around virus resembles the corona ring of the sun
37
What type of genome do coronaviruses have?
+ ssRNA genome
38
Are coronaviruses enveloped?
Yes! Remember - they have a glycoprotein ring, which is the envelope, and also looks liek the corona ring of the sun
39
How do the corona viruses replicate and cause pathology?
- Replicate in the epithelial cells of the respiratory tract.
- Very similar to Rhinoviruses in how they cause disease
40
What is the optimal temperature for the coronavirus?
33-35 degrees celsius
| means they replicate well in the UPPER respiratory tract, cooler than body temperature
41
What is the difference between the SARS coronavirus and the Non-SARS coronavirus?
The SARS virus is much more serious
- Grows better in warmer temperatures
- Infects the lower respiratory tract
42
How does transmission of the non-SARS coronavirus occur?
Through large droplets
43
What is the incubation period for the coronavirus?
3 days
44
During which seasons are outbreaks of the coronavirus most common?
Spring and winter
45
What populations are most commonly infected with the coronavirus?
Infants and children
46
What treatment options are available for coronavirus?
Same as rhinovirus - just aim to alleviate symptoms
47
Is there a vaccine available for the coronavirus?
No
48
Can reinfection occur despite circulating antibodies?
Yes
49
Do antibodies appear to have any lasting effect?
No
50
What is the adenovirus?
Another virus that can cause the common cold
51
Does the adenovirus have an envelope?
No
52
What type of genome does the adenovirus have?
dsDNA
53
Describe the shape of the adenovirus protein fibers
- The adenoviral fiber proteins protrude from the 12 vertices of the icosahedral capsid
- These are used for attachment and are toxic to cells
54
What is the function and purpose of the adenoviral fiber proteins?
This is a toxic protein for the cells – allows for causing cell death
55
How many different serotypes are there of the adenovirus?
Over 50
56
Which serotypes are the most common adenoviruses that cause respiratory distress?
1, 2 and 5
57
Which population is the adenovirus most prevalent in?
Children under 5
58
How is the adenovirus transmitted?
***
- Oral transmission
- Droplet inhalation
- Conjunctiva
59
The adenovirus is more commonly seen in the _______ than other cold viruses are
Eye
60
How does the adenovirus replication?
In epithelial cells - similar to others
61
What other tissues does the adenovirus enter, making it DIFFERENT from the other types?
***
It may enter the lymphoid tissues following acute infection
62
How long can individuals shed the adenovirus for following an infection?
18 months
It can spread widely during this time
63
Which age groups is the adenovirus more common in?
More common in young children
64
What is the seasonal pattern of the adenovirus?
NO seasonal pattern
***
65
What other diseases is the adenovirus associated with?
- Pharygoconjunctival fever
- Severe respiratory infections
- GI diseases (serotype 40 and 41)
66
What are the symptoms of pharyngoconjunctival fever?
Name tells you...
- Conjunctivitis
- Pharyngitis
- Fever
67
What severe respiratory infections are caused by the adenovirus?
- Croup
- Bronchiolitis
- Pneumonia
68
How can you treat the adenovirus?
Treatment are aimed at reducing symptoms
69
Is immunity of the adenovirus long-lived?
Immunity is long-lived, but serotype specific
About 50 serotypes, so not that effective
70
Is there a vaccine for the adenovirus?
Live oral vaccine to serotypes 4 and 7 for military recruits
Military recruits ONLY – adenovirus was causing common cold and more lower respiratory issues for them
71
What is the Coxsackievirus?
A virus of the enterovirus subfamily of picornaviruses that can also cause the common cold as well as other infections
***They can pass through the GI tract and survive and remain infective***
72
Is the Coxsackievirus enveloped?
No
73
What type of genome does the Coxsackievirus have?
+ ssRNA genome
74
How quickly can the Coxsackievirus replicate?
VERY RAPID
Replication occurs in the cytoplasm
75
Are Coxsackievirus able to survive at low pH?
Yes - can survive in the conditions of the GI tract
76
How is the Coxsackievirus transmitted?
*****
Transmitted through the fecal-oral route
***
77
Is there a vaccine for the Coxsackievirus?
No
78
How long does recovery take?
Couple weeks without treatment
79
What are the symptoms of herpangina from the Coxsackievirus?
- Abrupt onset fever
- Small vesicles on soft palate
- Small white ulcers form when vesicles rupture
80
How common is the Coxsackievirus? What age group?
Highest incidence in children 1-7 years old
It is a PEDIATRIC DISEASE ***
81
Are there any complications of herpangina?
In rare instances causative agent (Coxsackievirus) can cause meningitis or encephalitis.
82
What is hand, foot and mouth disease?
A disease caused by the Coxsackievirus - the name describes what it affects
83
What are the symptoms of hand, foot and mouth disease?
Symptoms
- Fever
- Vesicular lesions on the soles of hand and feet and on oral areas
84
What group is this disease most common in?
Children, but this is not always the case (Caretakers at daycare, for example)
85
What is the mode of transmission of hand, foot and mouth disease?
Probably oral-fecal transmission
86
What are the three other types of viruses that are responsible for the common cold?
1 - Influenza viruses (B and C)
2 - Respiratory syncytial virus (adults and school aged kids)
3 - Parainfluenza virus (adults and school aged kids)
87
So, what is a complete list of the seven viruses we discussed that are able to cause the common cold?
```
1 - Rhinovirus
2 - Coronavirus
3 - Adenovirus
4 - Coxsackievirus
5 - Influenza B and C
6 - Respiratory syncytial virus
7 - Parainfluenza virus
```
88
Which slide can I reference for a summary of what we just learned?
Slide 25
89
What is croup?
Laryngotracheobronchitis
Symptoms result from swelling in the subglottic region of the larynx
90
What virus causes croup?
Parainfluenza virus
91
What are the symptoms of croup?
- Fever
- Distinct brassy cough compared to a “seal’s bark”
- Inspiratory stridor
- Common cold-like symptoms (nasal discharge, mild cough, pharyngitis)
***
92
What will a radiograph of a child with croup show?
The radiograph will show a narrowing of the air shadow of trachea in the subglottic area
This is called “steeple sign”
***
93
What age group is at the most risk of developing croup?
Children younger than 6 years old
94
What is the clinically important complication of croup?
Hypoxia
95
What else will be on your list of differentials when you see a patient with symptoms and signs of croup?
- Noninfectious causes of airway obstruction
| - Bacterial epiglotitis (medical emergency - need to rule this out first)
96
Why do we worry about croup in children?
We worry about it more in kids because there is an increased risk of hypoxia – smaller the structures, smaller the airway, the less inflammation there can be before it starts to interfere with breathing
97
What is the treatment goal of croup?
Alleviate symptoms
98
What is the criteria that determine how you treat croup?
Whether or not the patient demonstrates stridor at rest
***
99
How do you treat a patient that does NOT have stridor at rest?
Non-severe case
- Humidified air
- Hydration (supportive treatment)
100
How do you treat a patient that DOES have stridor at rest?
Severe case - the three drug approach
- Oxygen
- Epinephrine
- Glucocorticoids
101
How is croup transmitted?
Respiratory secretions
102
What type of parainfluenza is the most common cause of croup?
Parainfluenza type 1
103
What other types of parainfluenza can cause croup?
Parainfluenza type 2 and 3
104
What else can parainfluenza type 3 cause?
Lower respiratory tract infections
105
What other types of viruses can cause croup?
Respiratory syncytial virus and the measles virus can both cause croup (not common)
106
What family is the parainfluenza virus from?
The paramyxovirus family
107
What type of viruses parainfluenza virus?
Helical nucleocapsid viruses
108
Do parainfluenza virus have envelopes?
YES - the envelope contains hemagglutinin and neuraminidase
109
What type of genome do we see with the parainfluenza virus?
- ssRNA genome
110
Where does RNA synthesis occur in parainfluenza viruses?
The cytoplasm
111
How areparainfluenza viruses transmitted?
Large droplets and direct contact
***
112
What is the incubation period for diseases of the parainfluenza virus?
2-10 days
113
What is the pathogenesis of the parainfluenza virus?
Infect and replicate in the ciliated epithelium of the respiratory tract
114
Does long term immunity occur with parainfluenza virus?
No - you will see short lived immunity following the infection, but reinfection usually results in a less severe illness (like a cold)
